Riyadh: The families of several imprisoned pro-reform activists in Saudi Arabia have drafted a letter to King Abdullah Bin Abdul Aziz asking him to either release their loved ones, jailed for over a year without charges, or bring them to trial.

The draft, made available on Tuesday, reminded King Abdullah of his pledge on becoming king in 2005 to set free all "prisoners of conscience" and also of the kingdom's international commitment to abide by universal human rights.

The letter, expected to be sent to the King on Saturday, listed 11 activists, including human rights advocates, lawyers and university professors, and was signed by 16 petitioners, mostly relatives or friends of the detained.

The families' move is a bold one in a country which leading watchdog groups say has a tainted human rights record. A researcher at the New York-based Human Rights Watch, Christoph Wilcke, said the "letter reflects the frustration of people who don't know why their loved ones are held."